Dynamic magnetic information storage or retrieval – General processing of a digital signal – Inter-record gap processing
Patent
1994-04-05
1996-12-10
Kim, W. C.
Dynamic magnetic information storage or retrieval
General processing of a digital signal
Inter-record gap processing
360 51, G11B 509
Patent
active
055837085
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to magnetic storage devices, and more particularly, to a circuit for detecting an unrecorded portion of a magnetic recording medium.
BACKGROUND ART
In general, a magnetic recording medium includes a sector identification code for distinguishing one sector from another. In addition, unrecorded portions are provided between respective sectors to separate one sector from the next. It should be noted that, since noise can be generated in these unrecorded portions of the magnetic recording medium, an appropriate sync signal may not be generated at the exact starting point of a sector. That is, the noise generated in the unrecorded portion may be mistaken for the starting point of a sector, by the playback circuit, and, as a result the sync signal may be generated in the unrecorded portion.
FIG. 1A represents the conventional data recording format of a hard disk.
In FIG. 1A, a post-amble portion exists from an end location ENDS to of a sector a starting point of an unrecorded portion DC-GAP, sequentially followed by an unrecorded portion, a pre-amble portion and a data portion of the next sector.
FIG. 1B shows the location where a normal sync signal should be generated when ready a conventional hard disk. As be seen from the figure, the normal sync signal is generated at a predetermined point of the pre-amble portion.
FIG. 2 shows the location where a sync signal is generated in reading a conventional hard disk when one or two noise pulses included in the unrecorded portion are mistaken for a data signal. Thus a conventional unrecorded portion detecting circuit of the recording medium erroneously generates a sync signal by recognizing as data pulses the noise pulses in the unrecorded portion of the recording medium.
DISCLOSURE OF THE INVENTION
Therefore, to solve the above problems, it is an object of the present invention to provide a circuit for detecting unrecorded in which, when portions of a recoding medium unrecorded portion is detected, a starting point of a sector is accurately detected by ignoring noise pulses, thereby generating a desired sync signal.
To accomplish the above object of the present invention, there is provided a circuit for detecting an unrecorded portion of a recording medium, comprising: signal comes from an unrecorded portion of the recording medium and for generating a window signal by counting a predetermined time; and which, if the number of pulses of the input signal is not less than a predetermined number, said sync signal generating means recognizes that the current input signal comes from a data region of the recording medium and generates a sync signal, while, if the number of pulses of the input signal is not more than a predetermined number, said sync signal generating means recognizes that the current input signal comes from the unrecorded region of the recording medium, fails to generate the sync signal.
BRIEF DESCRIPTION OF THE DRAWINGS
Other features and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings:
FIG. 1A represents a conventional data recording format for a hard disk;
FIG. 1B shows the location where a sync signal should be generated when a reading conventional hard disk;
FIG. 2 shows the location where a sync signal is in fact generated in a read operation of conventional hard disk when one or two noise pulses included in the unrecorded portion are mistaken for data signals;
FIG. 3 is a block diagram of one embodiment of an unrecorded portion detecting circuit according to the present invention; and
FIG. 4 is a timing diagram for explaining the operation of the unrecorded portion detecting circuit shown in FIG. 3.
DETAILED DESCRIPTION OF THE INVENTION
The preferred embodiment of an unrecorded portion detecting circuit according to the present invention will be described below in more detail with reference to the accompanying drawings.
In FIG. 3, an unrecorded portion detecting circuit according to the present
REFERENCES:
patent: 4081844 (1978-03-01), Devore et al.
patent: 4757406 (1988-07-01), Stewart et al.
patent: 4758906 (1988-07-01), Culp
patent: 4833551 (1989-05-01), Song
Kim W. C.
Samsung Electronics Co,. Ltd.
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